1. Field of the Invention
The present invention relates to an impact energy absorbing structure formed in an upper portion of a body of a motor vehicle and an impact energy absorbing member. More particularly, the invention relates to a structure and a member for absorbing impact energy in an upper vehicle body portion including a vehicle body structural member, such as a pillar, a roof side rail, a header or the like, and an interior trim, such as a pillar garnish, a roof lining or the like, that is spaced from the structural member by an interval extending toward the interior of a passenger compartment, and an energy absorbing member disposed within the interval.
2. Description of the Related Art
In motor vehicles, particularly passenger cars, an energy absorbing member is disposed in an interval space between an interior trim and a structural member of a vehicle body. Therefore, if an impact load is applied in a direction from the interior trim to the structural member, the energy absorbing member deforms to absorb energy of the impact load. Normally employed energy absorbing members are, for example, a grid rib member, a urethane pad, a steel member formed by bending a thin steel sheet so as to have a hat-like sectional shape, and the like. Also employed as an energy absorbing member is a generally-termed hybrid pipe (as described in U.S. Pat. No. 5,680,886) that is made up of a metal foil core member and sheets of a material other than metal that are laid on opposite side surfaces of the core member. In the hybrid pipe, the core member and the sheets on the opposite side surfaces of the core member are corrugated so that ridges (protruded portions) and grooves (recessed portions) alternate in a direction of an axis of the pipe.
The hybrid pipe, being hollow, has various excellent properties as an energy absorbing member. That is, the hollow hybrid pipe is light-weight, and easy to shape into a desired sectional shape. Furthermore, it is possible to adjust the load-displacement energy absorbing characteristic of a hybrid pipe by changing the pitch between adjacent protruded portions (recessed portions).